Used for the occasional reference to labels in graphical user interfaces, as well as user input.

Used for commands, URLs, filenames, file extensions, directory or folder names, emphasis, and new terms where they are defined.

Used for constructs from programming languages, HTML, and XML, both within running text and in listings.

Used for general placeholders that indicate that an item should be replaced by some actual value in your own program. Most importantly, this font is used for formal parameters when discussing the signatures of API methods.